This invention relates to a hydrometallurgical process for treating iron containing metal sulfides such as pyritic metal sulfides containing non-ferrous metal values for separate recovery of said non-ferrous metal values and sulfur values wherein said sulfur values can be selectively produced as elemental sulfur or in the form of sulfuric acid to supply acid requirements of the process.
Many processes are known for the hydrometallurgical extraction of desired metal values and sulfur from sulfide materials. These hydrometallurgical processes usually comprise the leaching of mineral concentrates at elevated temperatures and pressures in the presence of an oxidant in an acidic medium whereby the non-ferrous metal values can be extracted by dissolution and the sulfur can be removed in elemental form. Serious disadvantages of these known processes are the difficulties of dissolving pyritic copper and iron sulfides and of separating precipitated iron compounds from precious metals and dissolved non-ferrous metals. In most of the known processes, minerals such as chalcopyrite and pyrite are not directly soluble or require such severe leaching conditions that these processes become uneconomical.
Accordingly, it is a principal object of the present invention to provide a hydrometallurgical process for the treatment of pyritic metal sulfides containing pyrite, chalcopyrite, bornite, pyrrhotite and the like whereby the iron and non-ferrous metal values are rendered active for selective extraction and separate recovery.
It is another important object of the present invention to provide a substantially closed and self-supporting hydrometallurgical process for treatment of the aforesaid pyritic sulfides wherein sulfur values can be controllably produced as elemental sulfur or in the form of sulfuric acid to satisfy process acid requirements and to substantially obviate the discharge of sulfur-containing gases to the atmosphere.
A futher important object of the invention is the provision of a process which permits selective bulk removal of iron values from pyritic metal sulfides to enable subsequent recovery of non-ferrous metal sulfides in enriched and activated form with attendant economies in operating and capital costs.
Another important object of the present invention is the provision of a process for the treatment of pyritic copper sulfides for the recovery of copper values and precious metals together with metal sulfides such as zinc, cobalt and nickel sulfide and molybdenite.